Outdoor signs often must be lighted so that they will be visible at night. For example, it is desirable that advertising signs be visible after dark and it may be critical that traffic signs be visible. Various schemes of internally and externally illuminating such signs have been used. When external illumination is used, the most common method is to align a row of spotlights along either the bottom or the top of the sign. Those spotlights are positioned to direct light toward the sign. This provides several disadvantages, most notably the lack of uniformity of illumination. The sign will receive more light close to the spotlight than it will in other regions. A system providing uniform lighting would be desirable.
An additional problem is particularly acute in the case of overhead signs commonly used on multilane highways. Replacement of light sources commonly requires that traffic be diverted or stopped so that a worker can reach the light source to be replaced. A system with which the actual light source can be located beyond the traffic carrying portion of the highway would be advantageous.